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computations. In addition, the surveyor’s
compass was also developed to assist with
angle measurement – with less accuracy but
greater flexibility.
By the 1920s, optical theodolite technology
was rapidly improving through the work of
Switzerland’s Heinrich Wild. Beginning with
the T2 and T3, these instruments provided
accuracy and precision not previously
available to the surveyor. Other manufacturers
followed suit with similar instruments for
the next several decades and were used in
conjunction with the EDM for larger surveys.
Anticipation grew with the competition to see
which instrument company could marry the
theodolite and the EDM into one easy-to-use, The T3 theodolite was introduced in 1925. With its 10.5-inch telescope, this
yet accurate, optical instrument. theodolite had a range of up to 60 miles. It saw heavy use between 1952 and
1984. (Photo: NOAA)
Introducing the total station
Positions, everyone! Positions!
By the late 1960s, technology had firmly
entered the surveying world with a few Positional measurement has revolutionized not just the surveying profession,
electronic advancements. In 1968, Zeiss – a but a large portion of everyday tasks as well. From monitoring travel times
German company known for its lenses and for your commute to providing your food-delivery driver with your location,
optical systems – produced the first known position determination is the key element to these services. Satellite navigation
tachymeter, combining a theodolite with an is now the primary technology used for positioning, navigation and timing
electronic distance meter. The tachymeter (PNT) and a big part of most aspects of surveying.
became better known as the total station, as it
was capable of measuring angles and distances Remote sensing
in one instrument. While somewhat crude and Here is where we can discuss laser
hard to use, the Elta 14 total station introduced scanning and other remote sensing
the world to a future generation of surveying technologies. Remote sensing is the
instruments that would revolutionize the field. science and technology of gathering
data from a distance. Traditionally
In the course of a few years, several manufacturers this has been mostly done from
developed their own total stations. The biggest aircraft, satellites and vessels. However,
hurdle was combining the optics of the scope Image: NASA technology has expanded so that most
with the measuring axis of the EDM. By the end practitioners now consider the use of laser scanning, lidar, photogrammetry,
of the 1970s, most total stations were coaxial, hyperspectral cameras, bathymetric sonar and simultaneous localization
therefore measuring angles and distances was and mapping (SLAM) to be included in the category. Keep in mind that
done with one sighting.
all these technologies are types of measurements; they are not the vehicle or
Robotics were introduced in the early 1990s, instruments used for the measurement.
with two servo motors to drive the horizontal These various sensor types can collect millions of data points in a short
and vertical movements of the total station. amount of time. While surveyors are adapting to working with point clouds
These movements were controlled remotely and gigabytes/terabytes of data, it is a radical departure from our recent past
by the tracking system connected to the prism using only total stations and GNSS receivers. Significant advancements in
pole and data collector. Not requiring a human computer processing, data storage and programming have simplified the
being to remain stationary and manually manipulation of point clouds, but they remain a challenging task for even
operate the total station provided cost savings newer surveyors to tackle.
and additional efficiency for the field crew.

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EMPIRE STATE SURVEYOR / VOL. 58• NO 2/ 2022 • MARCH/APRIL 25